[PATCH 1/1] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32bit

[PATCH 1/1] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32bit

[Andy Whitcroft]

In 9e0e3c5130e9 ("x86/speculation, objtool: Annotate indirect calls/jumps
for objtool") we added annotations for CALL_NOSPEC/JMP_NOSPEC on x86 64bit.
We did not annotate the 32bit path.  Annotate it similarly.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
---
 arch/x86/include/asm/nospec-branch.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

    While reviewing indirect calls in our builds I noted that the
    i386 retpoline CALL_NOSPEC is not annotated safe even though
    its amd64 equivalent is.  I cannot see any reason this is not
    also inherantly safe.  Peter was there a reason that you did
    not annotate this one too?  Anyhow, on the assumption this was
    just missed, this patch annotates it.

    -apw

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index d0dabeae0505..07886162bdf8 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -183,7 +183,10 @@
  * otherwise we'll run out of registers. We don't care about CET
  * here, anyway.
  */
-# define CALL_NOSPEC ALTERNATIVE("call *%[thunk_target]\n",	\
+# define CALL_NOSPEC 						\
+	ALTERNATIVE(						\
+	ANNOTATE_RETPOLINE_SAFE					\
+	"call *%[thunk_target]\n",				\
 	"       jmp    904f;\n"					\
 	"       .align 16\n"					\
 	"901:	call   903f;\n"					\
-- 
2.15.1

Re: [PATCH 1/1] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32bit

[Peter Zijlstra]

On Wed, Mar 14, 2018 at 11:24:27AM +0000, Andy Whitcroft wrote:
> In 9e0e3c5130e9 ("x86/speculation, objtool: Annotate indirect calls/jumps
> for objtool") we added annotations for CALL_NOSPEC/JMP_NOSPEC on x86 64bit.
> We did not annotate the 32bit path.  Annotate it similarly.
> 
> Signed-off-by: Andy Whitcroft <apw@canonical.com>
> ---
>  arch/x86/include/asm/nospec-branch.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
>     While reviewing indirect calls in our builds I noted that the
>     i386 retpoline CALL_NOSPEC is not annotated safe even though
>     its amd64 equivalent is.  I cannot see any reason this is not
>     also inherantly safe.  Peter was there a reason that you did
>     not annotate this one too?  Anyhow, on the assumption this was
>     just missed, this patch annotates it.

Yeah, just an oversight aided by the fact that I (obviously) never build
32bit kernels.

> diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
> index d0dabeae0505..07886162bdf8 100644
> --- a/arch/x86/include/asm/nospec-branch.h
> +++ b/arch/x86/include/asm/nospec-branch.h
> @@ -183,7 +183,10 @@
>   * otherwise we'll run out of registers. We don't care about CET
>   * here, anyway.
>   */
> -# define CALL_NOSPEC ALTERNATIVE("call *%[thunk_target]\n",	\
> +# define CALL_NOSPEC 						\
> +	ALTERNATIVE(						\
> +	ANNOTATE_RETPOLINE_SAFE					\
> +	"call *%[thunk_target]\n",				\
>  	"       jmp    904f;\n"					\
>  	"       .align 16\n"					\
>  	"901:	call   903f;\n"					\

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Re: [PATCH 1/1] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32bit

[Ingo Molnar]

* Peter Zijlstra <peterz@infradead.org> wrote:

> On Wed, Mar 14, 2018 at 11:24:27AM +0000, Andy Whitcroft wrote:
> > In 9e0e3c5130e9 ("x86/speculation, objtool: Annotate indirect calls/jumps
> > for objtool") we added annotations for CALL_NOSPEC/JMP_NOSPEC on x86 64bit.
> > We did not annotate the 32bit path.  Annotate it similarly.
> > 
> > Signed-off-by: Andy Whitcroft <apw@canonical.com>
> > ---
> >  arch/x86/include/asm/nospec-branch.h | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> >     While reviewing indirect calls in our builds I noted that the
> >     i386 retpoline CALL_NOSPEC is not annotated safe even though
> >     its amd64 equivalent is.  I cannot see any reason this is not
> >     also inherantly safe.  Peter was there a reason that you did
> >     not annotate this one too?  Anyhow, on the assumption this was
> >     just missed, this patch annotates it.
> 
> Yeah, just an oversight aided by the fact that I (obviously) never build
> 32bit kernels.
> 
> > diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
> > index d0dabeae0505..07886162bdf8 100644
> > --- a/arch/x86/include/asm/nospec-branch.h
> > +++ b/arch/x86/include/asm/nospec-branch.h
> > @@ -183,7 +183,10 @@
> >   * otherwise we'll run out of registers. We don't care about CET
> >   * here, anyway.
> >   */
> > -# define CALL_NOSPEC ALTERNATIVE("call *%[thunk_target]\n",	\
> > +# define CALL_NOSPEC 						\
> > +	ALTERNATIVE(						\
> > +	ANNOTATE_RETPOLINE_SAFE					\
> > +	"call *%[thunk_target]\n",				\
> >  	"       jmp    904f;\n"					\
> >  	"       .align 16\n"					\
> >  	"901:	call   903f;\n"					\
> 
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Applied, thanks guys!

	Ingo

[tip:x86/pti] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32-bit kernels

[tip-bot for Andy Whitcroft]

Commit-ID:  a14bff131108faf50cc0cf864589fd71ee216c96
Gitweb:     https://git.kernel.org/tip/a14bff131108faf50cc0cf864589fd71ee216c96
Author:     Andy Whitcroft <apw@canonical.com>
AuthorDate: Wed, 14 Mar 2018 11:24:27 +0000
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 14 Mar 2018 13:24:31 +0100

x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32-bit kernels

In the following commit:

  9e0e3c5130e9 ("x86/speculation, objtool: Annotate indirect calls/jumps for objtool")

... we added annotations for CALL_NOSPEC/JMP_NOSPEC on 64-bit x86 kernels,
but we did not annotate the 32-bit path.

Annotate it similarly.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180314112427.22351-1-apw@canonical.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/nospec-branch.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index b7063cfa19f9..b3996d60f981 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -183,7 +183,10 @@
  * otherwise we'll run out of registers. We don't care about CET
  * here, anyway.
  */
-# define CALL_NOSPEC ALTERNATIVE("call *%[thunk_target]\n",	\
+# define CALL_NOSPEC						\
+	ALTERNATIVE(						\
+	ANNOTATE_RETPOLINE_SAFE					\
+	"call *%[thunk_target]\n",				\
 	"       jmp    904f;\n"					\
 	"       .align 16\n"					\
 	"901:	call   903f;\n"					\

Re: [tip:x86/pti] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32-bit kernels

[Josh Poimboeuf]

On Wed, Mar 14, 2018 at 05:28:01AM -0700, tip-bot for Andy Whitcroft wrote:
> Commit-ID:  a14bff131108faf50cc0cf864589fd71ee216c96
> Gitweb:     https://git.kernel.org/tip/a14bff131108faf50cc0cf864589fd71ee216c96
> Author:     Andy Whitcroft <apw@canonical.com>
> AuthorDate: Wed, 14 Mar 2018 11:24:27 +0000
> Committer:  Ingo Molnar <mingo@kernel.org>
> CommitDate: Wed, 14 Mar 2018 13:24:31 +0100
> 
> x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32-bit kernels
> 
> In the following commit:
> 
>   9e0e3c5130e9 ("x86/speculation, objtool: Annotate indirect calls/jumps for objtool")
> 
> ... we added annotations for CALL_NOSPEC/JMP_NOSPEC on 64-bit x86 kernels,
> but we did not annotate the 32-bit path.
> 
> Annotate it similarly.

This patch has no effect because objtool only supports 64-bit kernels.

-- 
Josh

Re: [tip:x86/pti] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32-bit kernels

[Ingo Molnar]

* Josh Poimboeuf <jpoimboe@redhat.com> wrote:

> On Wed, Mar 14, 2018 at 05:28:01AM -0700, tip-bot for Andy Whitcroft wrote:
> > Commit-ID:  a14bff131108faf50cc0cf864589fd71ee216c96
> > Gitweb:     https://git.kernel.org/tip/a14bff131108faf50cc0cf864589fd71ee216c96
> > Author:     Andy Whitcroft <apw@canonical.com>
> > AuthorDate: Wed, 14 Mar 2018 11:24:27 +0000
> > Committer:  Ingo Molnar <mingo@kernel.org>
> > CommitDate: Wed, 14 Mar 2018 13:24:31 +0100
> > 
> > x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32-bit kernels
> > 
> > In the following commit:
> > 
> >   9e0e3c5130e9 ("x86/speculation, objtool: Annotate indirect calls/jumps for objtool")
> > 
> > ... we added annotations for CALL_NOSPEC/JMP_NOSPEC on 64-bit x86 kernels,
> > but we did not annotate the 32-bit path.
> > 
> > Annotate it similarly.
> 
> This patch has no effect because objtool only supports 64-bit kernels.

Yeah, indeed - but it's still a good change for completeness, right?

Thanks,

	Ingo

Re: [tip:x86/pti] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32-bit kernels

[Josh Poimboeuf]

On Wed, Mar 14, 2018 at 02:39:43PM +0100, Ingo Molnar wrote:
> 
> * Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> 
> > On Wed, Mar 14, 2018 at 05:28:01AM -0700, tip-bot for Andy Whitcroft wrote:
> > > Commit-ID:  a14bff131108faf50cc0cf864589fd71ee216c96
> > > Gitweb:     https://git.kernel.org/tip/a14bff131108faf50cc0cf864589fd71ee216c96
> > > Author:     Andy Whitcroft <apw@canonical.com>
> > > AuthorDate: Wed, 14 Mar 2018 11:24:27 +0000
> > > Committer:  Ingo Molnar <mingo@kernel.org>
> > > CommitDate: Wed, 14 Mar 2018 13:24:31 +0100
> > > 
> > > x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32-bit kernels
> > > 
> > > In the following commit:
> > > 
> > >   9e0e3c5130e9 ("x86/speculation, objtool: Annotate indirect calls/jumps for objtool")
> > > 
> > > ... we added annotations for CALL_NOSPEC/JMP_NOSPEC on 64-bit x86 kernels,
> > > but we did not annotate the 32-bit path.
> > > 
> > > Annotate it similarly.
> > 
> > This patch has no effect because objtool only supports 64-bit kernels.
> 
> Yeah, indeed - but it's still a good change for completeness, right?

Yeah, it's fine.  Objtool won't use it, but I suppose it makes the code
less surprising and more consistent for humans.

-- 
Josh